And Moses brought Aaron and his sons, and washed them with water. (Leviticus 8:6)
Moses brings Aaron and his sons to the laver for washing. He gives them a bath, if you please. This signifies that they are to be holy, pure, and clean if they are to serve the Lord. They have already been to the altar for forgiveness, but they need cleansing.
A great many people today say that they are qualified for service because they are saved. Now it is true that salvation is the prime requisite, but for service one must also be cleansed. You must be cleansed to be used! Listen to these verses from Scripture:
Not by works of righteousness which we have done, but according to his mercy he saved us, by the washing of regeneration, and renewing of the Holy Ghost. (Titus 3:5)
Let us draw near with a true heart in full assurance of faith, having our hearts sprinkled from an evil conscience, and our bodies washed with pure water. (Hebrews 10:22)
That he might sanctify and cleanse it with the washing of water by the word. (Ephesians 5:26)
Jesus saith to him, He that is washed needeth not save to wash his feet, but is clean every whit: and ye are clean, but not all. (John 13:10)
If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness. (1 John 1:9)
The Holy Ghost renews us as we go along, but we need a washing from the Lord. With what does He wash us? What is the cleansing agent? It is the Word of God. That is what cleanses us. The Lord said that His disciples needed to be washed because their feet were dirty. They all had a bath; that is, they all had been saved (except Judas), but they still needed their feet washed so that they might have fellowship with Him. This cleansing is for service.
How do we get that washing? It is by confession that we are forgiven and cleansed. Do you want to be used of God? Then go confess your sins, dear Christian. That is the first step. This is God’s way. This is His command. We either must do it His way or we cannot be of service. He has His way of doing things and we need to learn and obey His ways.
—From Edited Messages on Leviticus by J. Vernon McGee